Sheet manufacturing apparatus, and sheet manufacturing method

Abstract

A sheet manufacturing apparatus suppresses material being left in a material supply conduit while manufacturing sheets with uniform grammage. A sheet manufacturing apparatus includes: a rotatable, foraminous drum unit; a web forming unit configured to form a web using material including fiber that has passed through the holes in the drum unit; and a material supply conduit having a connector that connects to the drum unit, and carrying material including fiber into the drum unit by air flow; the velocity of the flow in the connector being lower than the velocity of the flow on the upstream side of the connector.

The invention claimed is: 
     
       1. A sheet manufacturing apparatus comprising:
 a rotatable, foraminous drum unit; 
 a web forming unit configured to form a web using material including fiber that has passed through the holes in the drum unit; and 
 a material supply conduit having a connector that connects to the drum unit, and carrying material including fiber into the drum unit by air flow; 
 the velocity of the air flow in the connector being lower than the velocity of the air flow on the upstream side of the connector. 
 
     
     
       2. The sheet manufacturing apparatus according to  claim 1 , wherein:
 a first supply conduit of the material supply conduit splits at a junction into a second supply conduit and a third supply conduit; 
 the second supply conduit and third supply conduit both connect to the drum unit; and 
 the velocity of the air flow in the second supply conduit and third supply conduit is less than the velocity of the air flow in the first supply conduit. 
 
     
     
       3. The sheet manufacturing apparatus according to  claim 2 , wherein:
 the second supply conduit connects to the drum unit at one end of the axis of rotation; 
 the third supply conduit connects to the drum unit at the other end of the axis of rotation; 
 and the second supply conduit and third supply conduit are symmetrical to a virtual plane through the junction and perpendicular to the axis of rotation of the drum unit. 
 
     
     
       4. The sheet manufacturing apparatus according to  claim 2 , wherein:
 the junction is above the axis of rotation of the drum unit. 
 
     
     
       5. The sheet manufacturing apparatus according to  claim 1 , wherein:
 the internal sectional area of the connector is greater than the internal sectional area of the material supply conduit on the upstream side of the connector. 
 
     
     
       6. The sheet manufacturing apparatus according to  claim 5 , wherein:
 the material supply conduit has a transition wherein the internal sectional area increases gradually from the upstream side to the downstream side. 
 
     
     
       7. The sheet manufacturing apparatus according to  claim 1 , wherein:
 the connector has a bend. 
 
     
     
       8. The sheet manufacturing apparatus according to  claim 7 , wherein:
 the bend connects to the drum unit above the axis of rotation of the drum unit. 
 
     
     
       9. The sheet manufacturing apparatus according to  claim 1 , further comprising:
 a mixer configured to mix fiber and additive in air; 
 the web forming unit laying a web using material including fiber and additive; and 
 the mixer being located above the axis of rotation of the drum unit. 
 
     
     
       10. A sheet manufacturing apparatus comprising:
 a rotatable, foraminous drum unit including a screen that is rotatable around a rotation axis and a pair of side walls to which the screen is rotatable coupled, at least one of the side walls having an opening that penetrates completely through the at least one of the side walls in a direction along the rotation axis; 
 a web forming unit configured to form a web using material including fiber that has passed through the holes in the drum unit; and 
 a material supply conduit having a connector that connects to the at least one of the side walls such that material including fiber is carried through the opening into the drum unit by air flow; 
 the internal sectional area of the connector being greater than the internal sectional area of the material supply conduit on the upstream side of the connector. 
 
     
     
       11. A sheet manufacturing apparatus comprising:
 a rotatable, foraminous drum unit including a screen that is rotatable around a rotation axis and a pair of side walls to which the screen is rotatable coupled, at least one of the side walls having an opening that penetrates completely through the at least one of the side walls in a direction along the rotation axis; 
 a web forming unit configured to form a web using material including fiber that has passed through the holes in the drum unit; 
 an air flow generator that produces an air flow to carry material including fiber; and 
 a material supply conduit configured to carry material including fiber into the drum unit by the air flow produced by the air flow generator; 
 the material supply conduit having a first part with an inside of a first sectional area, and
 a second part with an inside of a second sectional area that is larger than the first sectional area, and 
 the second part being disposed closer to the drum unit than the air flow generator and connecting to the at least one of the side walls such that the material including fiber is carried through the opening into the drum unit by the air flow. 
 
 
     
     
       12. The sheet manufacturing apparatus according to  claim 11 , wherein:
 the conveyance length of the second part is three times or greater than the internal width of the second part. 
 
     
     
       13. A sheet manufacturing apparatus comprising:
 a rotatable, foraminous drum unit; 
 a web forming unit configured to form a web using material including fiber that has passed through the holes in the drum unit; and 
 a material supply conduit configured to carry material including fiber into the drum unit by air flow; 
 the material supply conduit having a first supply conduit,
 a second supply conduit branching from the first supply conduit at a junction, and connecting to the drum unit at one end of the axis of rotation, and 
 a third supply conduit branching from the first supply conduit at the junction, and connecting to the drum unit at the other end of the axis of rotation; 
 
 the second supply conduit and third supply conduit having, at the end closer to the drum unit than the junction, a part where the internal sectional area is greater than the sectional area of the interface between the first supply conduit and the junction. 
 
     
     
       14. The sheet manufacturing apparatus according to  claim 13 , wherein:
 the conveyance length of the larger sectional area part is three times or greater than the width of the larger part. 
 
     
     
       15. A sheet manufacturing method comprising:
 a step of supplying material including fiber by air flow into a rotatable, foraminous drum unit; and 
 a step of forming a web using material including fiber that has passed through the holes in the drum unit; 
 the step of supplying material including fiber into the drum unit supplying the material into the drum unit by an air flow of a second velocity that is slower than the first velocity after conveying the material by an air flow of a first velocity.